Olivia Newton-JohnAge: 63Occupation: Singer, Songwriter, and ActressKnown For: Winning four Grammy Awards for songs such as ‘I Honestly Love You’ and ‘Physical,’ starring in the smash movie musical ‘Grease,’ being a breast cancer survivor, and her work as an environmental and animal rights activist

Serena WilliamsAge: 30Occupation: Professional Tennis PlayerKnown For: Being ranked the number one female player on five separate occasions, winning 27 Grand Slam titles, earning more career prize money than any other female athlete in history, and being the sister of fellow player Venus Williams